Back to the Future II: not necessarily a digital alteration but definitely a visual one.
The original: featuring “Coming Summer 1990”, as seen at the end of the theatrical and home video versions, including the Blu-ray:
Removed from the version shown in recent years by ITV (UK) and the “BTTF Part III” logo also appears to have been altered from the original.
This is an alteration, but I don’t think this is a recent change. It was actually more recently that the “Coming Summer 1990” was restored after years of it not having been included. I first became aware of it on the 25th Anniversary Blu-ray set and corresponding DVD set. It was not present on the 2002 DVDs or any previous VHS release I have ever seen. I believe it appeared in theaters this way and then was removed for it’s initial video release which is how it remained until 2011.